The latest aircraft noise exposure maps from the Port of Seattle show that aircraft noise is decreasing in Des Moines.

The city of Des Moines may soon modify their 15-year-old building codes concerning airport noise control.

“Airplanes are getting quieter … and the third runway supports more incoming flights than take-offs,” said City Manager Tony Piasecki.

Without the noise levels, the council no longer saw a need for stringent noise reduction requirements for building in their city.

At the March 1 Des Moines City Council meeting Grant Fredricks, Planning, Building & Public Works director, presented new data from the Port of Seattle’s “Part 150” study to the council. The data shows a significant amount of reduction in air traffic noise for the southern part of Des Moines.

The “Part 150” study was developed by the Port in the ‘90s to identify areas of high-level air traffic noise in the Sea-Tac Airport’s surrounding cities and neighborhoods. The ongoing study provides communities with current sound data for the areas in their flight corridor.

When the noise ordinances were originally put in place the city was divided into two areas-- Area I and Area II.

Based on the data received from the Port the City Council decided to eliminate Area II. According to the maps, “In 2016 there will be no air traffic noise over 60 decibels,” Councilwoman Carmen Scott noted.

For this reason the city has decided to eliminate Area II and make Area I an advisory area. The boundaries for Area I will also move north by several blocks from S. 252nd St. to Kent/Des Moines Rd.

The advisory area will have no building requirements for heightened noise control outside of King County’s standard building code or the International Building Code (IBC) for this area of Des Moines. Builders will receive an advisory notice with their permits and a list of recommendations.

Previously builders and remodelers in Des Moines had to follow strict sound transmission control requirements to lessen the noise inside of the structure. This entailed using 2 x 6s instead of 2 x 4s for framing, double-doors and double-windows, and much more; all of these being very costly building materials.

“Making it [ordinance] advisory would make it more accessible to get permits and to do the work properly and to code,” said Councilwoman Melissa Musser. Musser fully supported the idea of lightening the financial burden for homeowners.

However, Fredricks noted the benefit of having the city’s help through the permit process with guaranteeing workmanship and quality by a city inspector.

Scott thinks there needs to be some sort of record kept by the city of the upgrades made to homes and buildings for sound control. Approximately 95 percent of these areas have been built or completely rebuilt to meet the higher standard of building required over the last 15 years,

“Homes built to the previous, more stringent code is a real estate selling point. It gives tremendous energy efficiency and quietness,” said Scott.

The draft ordinance will be completed this spring and a public hearing will be held on a date not yet determined.

The federal programs for noise reduction in areas with a noise level over 65 decibels will still be in effect. The changes will on affect the codes and ordinances for Des Moines.

The Port is working with the airport’s neighboring communities and citizens. According to their website, in Des Moines they have three permanent noise monitoring stations.

Comments on airport noise may be sent to SEApart150comments@landrum-brown.com. Additional information about the Part 150 project can be found at http://www.airportsites.net/SEA-Part150.